Is RAM the solution?
Firstly you need to determine whether the bottleneck actually is the RAM.... This is dependent on operating system - if Windows you can use Resource Monitor to view how much is in use. On Linux you could use 'top' or System Monitor - either should give you what you need. The key is to see whether Blender is using up all of the 'free' memory - and causing swapping out to disk - you'll see the 'free' drop away to zero and disk activity drastically increase if that is the case. If you have free memory available while baking then the problem isn't the amount of RAM but elsewhere - so increasing the RAM won't give you any benefit in that area (but could still be useful elsewhere!)